What crypto assets actually are
You know how state changes and how the network agrees on it. This is what is being tracked.
Beginners file all of this under "crypto" and assume the differences are branding. They are not — but they are also not five mutually exclusive buckets. One asset can answer several questions at once: USDC is a token, a stablecoin, an ERC-20 and fungible, and it can be held custodially or self-custodially.
The distinction everything hangs on
A native asset is built into the blockchain itself. A token is an asset whose balances and rules are implemented by a smart contract.
Learning objectives
- Distinguish a coin from a token, and explain why the distinction is structural
- Classify an asset by how it exists, its common token role or shape, and who controls the keys
- Explain why a stablecoin carries risks a native asset does not
- Explain the difference between custodial and self-custodial holdings
Core
Coins and tokens are not the same shape
Native assets are built into the protocol. ETH is not stored in a contract — ETH balances are part of Ethereum's state, at the same level as the chain itself.
Tokens are created by smart contracts. A token contract is a program holding a table of who owns how much. USDC on Ethereum is one contract's ledger.
| Aspect | Native asset (ETH) | Token (USDC) |
|---|---|---|
| Exists because | The protocol says so | A contract says so |
| Can be frozen by an issuer | No | Yes, if the contract allows it |
| Can be lost to a contract bug | No | Yes |
| Pays the transaction fee | Yes | No — you need ETH to pay the fee as well |
Every beginner hits this once
Holding only USDC on Ethereum means you cannot move it. Moving it requires calling a contract, calling a contract requires gas, and the resulting transaction fee is paid in ETH.
Three questions to ask about any asset
Ask these questions in order:
- How does it exist? Is it a native asset built into the chain, or a token created by a contract?
- If it is a token, what role or shape does it have? Stablecoin, governance token, wrapped asset and NFT are common examples, not one exhaustive taxonomy.
- Who controls the keys? Custodial and self-custodial describe who can authorise activity; this axis cuts across the others.
These labels can overlap. WETH is a token, a wrapped asset, an ERC-20 and a fungible asset. The point is to describe the asset accurately rather than force it into one bucket.
The chain's own asset. Pays fees, secures the network, understood by the protocol itself.
| Asset | Chain | Note |
|---|---|---|
| BTC | Bitcoin | Deliberately limited. Designed to be money and little else |
| ETH | Ethereum | Pays transaction fees, and is staked to secure the network |
| SOL | Solana | Same roles on Solana |
No issuer. Nobody can freeze your BTC or reverse your ETH transfer — and nobody can help you if you lose your keys.
Tokens designed to hold a steady value, almost always one US dollar.
| Asset | Issuer | Model |
|---|---|---|
| USDC | Circle | Cash and short-term US treasuries, with public attestations |
| USDT | Tether | Backed by reserves; the largest by volume |
Why they matter. Native assets move in price, which makes them awkward as money — nobody wants to be paid in something worth 20% less by Friday. Stablecoins give a stable unit that still moves at blockchain speed. Most real-world payment usage runs through them.
And the trade-off. A dollar-backed stablecoin is a claim on an issuer. Holding USDC means trusting the blockchain, the token contract, and Circle — that reserves exist and redemption is honoured.
That third one is new. It is a centralised trust assumption inside a decentralised system, and it is not hidden — it is the deal. Regulated issuers can and do freeze addresses when compelled by law enforcement.
Tokens tied to a specific application, usually carrying a vote over how it changes.
| Asset | Protocol | Roughly |
|---|---|---|
| UNI | Uniswap | Governance over the Uniswap protocol |
| AAVE | Aave | Governance, and a role in the safety module |
What a governance token actually entitles you to varies enormously, and is often less than the marketing implies. Week 4 covers this properly. For now: holding one is participation in a decision process, which is a different kind of thing from holding money.
A token that represents another asset, so it can be used where the original cannot.
| Asset | Represents | Why it exists |
|---|---|---|
| WETH | ETH | ETH is native, so it doesn't follow the token standard contracts expect |
| WBTC | BTC | Bitcoin can't run Ethereum contracts |
WETH
WBTCWETH is mechanically simple: deposit ETH into the contract, receive WETH, and redeem it through the same contract. Unlike custodial wrapped assets, there is no external custodian holding the underlying ETH; the main dependency is the contract itself.
WBTC is a different animal. Real BTC sits on Bitcoin, held by a custodian, while a token on Ethereum represents it. That token is worth a bitcoin only as long as the custodian holds the bitcoin and honours redemption.
Fungible means interchangeable — any 1 USDC is any other. Non-fungible means each unit is individually distinct.
Uses go well beyond profile pictures: event tickets, in-game items, domain names like ENS, credentials, ownership records.
The most common NFT misconception
The image is usually not on the blockchain. Storing images on-chain is prohibitively expensive, so the token typically holds a link. If whatever hosts that file disappears, the token remains and the picture does not.
Custodial versus self-custodial
Cutting across the categories above: who holds the keys?
| Aspect | Custodial | Self-custodial |
|---|---|---|
| Who holds the keys | An exchange or company | You |
| What you have | An account balance and a claim | The asset itself |
| Lose access / forget local wallet password | Account/support recovery may help | A recovery phrase or valid key backup can restore access; without a valid backup, no support desk can restore it |
| Custodian / exchange fails | You depend on that custodian and may become a creditor | Not directly exposed to that custodian; issuer/token risks may still remain |
| Token-level controls | The platform may freeze its account | An issuer may still freeze its token |
If you buy ETH on an exchange and leave it there, you do not directly control the on-chain ETH. The exchange controls custody on your behalf, while your account records a claim or balance with the exchange. Usually equivalent. In the cases where they diverge — and there is a long history of exchange failures where they diverged badly — the difference is everything. Self-custody removes the platform's custody control, but it does not remove token-level controls built into an asset such as a stablecoin.
"Not your keys, not your coins"
This is not advice to move everything to self-custody. Self-custody transfers the entire security burden to you, and Week 0 Part 4 explains how much burden that is. It is a statement about what you own — and both options are legitimate for different purposes.
Landscape
- Meme coins — tokens whose demand is driven largely by attention and community. When attention leaves, liquidity and price can fall quickly
- RWA — real-world assets like treasuries or property represented on-chain. The token cannot remove the legal and custody arrangements around the underlying asset
- LSTs — liquid staking tokens, representing staked assets while staying tradable. Their value also depends on the staking system and redemption path
- Algorithmic stablecoins — tokens aiming for stability through rules or incentives rather than straightforward reserves. A broken design can lose its peg, as Terra/UST did in 2022
- ERC-20 / ERC-721 / ERC-1155 — standards that give applications common token interfaces. They improve interoperability, but do not make every token safe or liquid. Week 3
- Token supply terms — circulating, total and fully diluted supply measure different things. Comparing the wrong one can make a project's scale or future dilution look misleading
Worked example
One person's holdings, sorted by what could actually go wrong. The risks differ in kind, not just in size.
| Holding | Category | What has to hold up |
|---|---|---|
| 0.5 ETH in their own wallet | Native, self-custodial | Ethereum works; they keep their keys safe |
| 200 USDC in the same wallet | Stablecoin, self-custodial | The above, plus the contract works, plus Circle holds reserves |
| 100 UNI in the same wallet | Governance, self-custodial | The above, minus the issuer |
| 0.01 BTC on an exchange | Native, custodial | Bitcoin works, and the exchange stays solvent |
| 1 NFT in their wallet | Non-fungible | Ethereum works, keys safe, and someone keeps hosting the image |
Five holdings, five failure modes. The exchange BTC is the only holding here exposed to exchange-custodian bankruptcy risk. The USDC is the only one where an issuer could freeze you. The NFT is the only one that can silently become a broken link.
This is the actual skill
Being able to build this table for anything you hold. Week 2 Part 6 generalises it into a tool you can point at anything.
Further exploration — optional, not assessed
- ethereum.org — Stablecoins — the models compared, including algorithmic
- ethereum.org — NFTs — uses beyond collectibles
- ethereum.org — What is ether — why the native asset is structurally different
- Tokenomics — supply schedules, emissions, incentive design. A large field, deliberately not compulsory
Sources and attribution
- ethereum.org — Stablecoins — Reuse (CC BY 4.0), adapted
- ethereum.org — ERC-20 token standard — Reuse (CC BY 4.0), adapted
- ethereum.org — NFTs — Reuse (CC BY 4.0), adapted
- ethereum.org — What is ether — Reuse (CC BY 4.0), adapted
- Web3 Internship Handbook — Reuse (permission granted); CryptoPunks visual adapted with permission
Named assets are illustrative examples chosen for recognisability, not recommendations. Nothing here is financial advice.